private string CalculateGmtOffset()
{
char c = '+';
DateTime dateTime = this.ToDateTime();
TimeSpan timeSpan = TimeZone.CurrentTimeZone.GetUtcOffset(dateTime);
if (timeSpan.CompareTo(TimeSpan.Zero) < 0)
{
c = '-';
timeSpan = timeSpan.Duration();
}
int hours = timeSpan.Hours;
int minutes = timeSpan.Minutes;
return(string.Concat(new object[]
{
"GMT",
c,
DerGeneralizedTime.Convert(hours),
":",
DerGeneralizedTime.Convert(minutes)
}));
}